1. Field of the Invention
This invention relates to a venetian blind, the slats of which can be tilted to different angles relative to one another (i.e., variably tilted). When the slats of such a blind have been tilted, so that they are closed in a normal fashion, the slats of a lower portion of the blind, in front of a room window, can be tilted to an open position to provide a view of the outside, while at the same time, the slats of the blind's upper portion can be left tilted in a closed position to reduce the amount of sunlight coming into the room. Alternatively, an upper portion of the blind can be tilted to an open position to admit some sunlight into the room, while at the same time, the slats of the blind's lower portion can be left tilted in a closed position to provide privacy in the room and/or reduce the amount of sunlight in the room, for example to prevent glare from interfering with the use of computer or television screens in the room.
2. Description of the Art
Venetian blinds have generally included: a horizontally-elongated head rail; a plurality of horizontally-elongated slats beneath the head rail and parallel to it; and at least two slat-supporting ladders movably suspended from the head rail and supporting the slats in vertically spaced apart relationship. In this regard, each ladder generally has had front and rear, vertically-extending members that have been connected to each other by a plurality of vertically-spaced cross-rungs. Supported on each cross-rung, between the vertically-extending members of its ladder, has been one length-wise side of a slat. The head rail generally has had an adjusting mechanism for moving the ladders, so that the vertically-extending members of each ladder move in opposite vertical directions relative to one another, to pivot each slat about its length-wise axis.
It has also been known to provide a venetian blind with a vertically-extending auxiliary tilt cord to provide variable tilting of its slats. The auxiliary tilt cord has been adapted to engage at least one of the vertically-extending members of the blind's ladders, at an intermediate location along its height, and when manipulated, to adjust the angle of pivot of the slats below the intermediate location. See U.S. Pat. Nos. 2,427,266, 2,719,586, 2,751,000, 4,940,070, EP 0 620 355 and JP(A) 8-210060. Although such a blind has been reasonably successful in providing a room with both privacy and some sunlight, the blind has generally been rather complicated to manufacture and use.